A leading supplier of plumbing fittings, Mc Alpine comes with a variety of high-quality and competitive products to suit all plumbing solutions. Ventapipe 25 air admittance valves is an efficient alternative to anti-syphon. It also can be used to reseal traps and to ventilate the waste pipe system in order to overcome problems such as noisy discharge or loss of trap seal caused by induced or self siphonage.